The present invention generally relates to treadmill exercise apparatus, and in its preferred embodiments more specifically relates to a treadmill with pivoting bed assembly in which a cam actuated mechanism is provided to balance the weight of the bed assembly during lowering and raising operations.
The use of treadmills is well known in the prior art, and they have been widely used exercise devices. The basic treadmill design incorporates a bed assembly with a continuous moving belt, driven by a motor, that runs in a shallow loop over rollers mounted at each end of a base frame of sufficient length to allow a user to walk or run freely in place as the belt moves. The basic treadmill also typically includes a generally upright assembly at the front of the bed assembly, usually incorporating handles that may be grasped by the user for stability, and may also include various controls and instruments. Typically, both the speed of the belt and the elevation of the front of the bed may be adjusted to allow the user to vary both rate of movement and the angle of the walking or running surface.
With the increased concern for fitness that has become prevalent in recent years, treadmills have become increasingly popular as home exercise devices. Although treadmills are very effective for that purpose, there is a disadvantage in a home setting arising from their size and the relatively large area of floor space they occupy. In an effort to overcome that disadvantage, treadmill designs with folding beds have been introduced. In typical folding bed designs the bed assembly is pivoted at the front end, that adjoins the upright support assembly, so that the entire bed assembly, including the motor, frame, belt, and bed support structure, can be folded to a vertical or near vertical position. The folding bed assembly approach addresses the space problem with reasonable effectiveness, but also introduces its own set of disadvantages. Especially in treadmills that provide effective support for walking or running, the weight of the bed assembly is substantial, and substantial force is required to lift the bed assembly to an upright position as well as to safely lower it to an unfolded position. The risk of injury from the strain of lifting and/or from the bed falling if dropped during the lifting or lowering process or if improperly secured in an upright position is significant.
Various approaches toward overcoming the problems with the folding treadmill concept have been tried, with some degree of success. In one approach, a motor is used to raise and lower the bed assembly, which is effective, but increases the cost of the treadmill significantly. In another approach, the bed assembly is spring biased toward the upright position. This approach is effective in reducing the lifting force required, but the bed assembly must be forced into an opened position to overcome the biasing force, and should be locked in the unfolded position for stability and safety, introducing another set of disadvantages for easy and safe operation.
There remains a need for a folding treadmill that addresses and overcomes the disadvantages of the prior art, that requires little force to open for use and to fold for storage, and that is safe during the folding procedure (both opening and closing), during use, and during storage.
The present invention provides a folding treadmill that includes a stationary frame assembly with a supporting base and an upright member or members connected to and extending upwardly from the supporting base, and that also includes a bed assembly pivotally connected at one end to the stationary frame so that the bed assembly can be rotated around that pivotal connection between a closed position, for storage, and an open position, for use of the treadmill, encompassing a rotational range of approximately ninety degrees. In the treadmill of the invention the bed assembly is manually raised and lowered, requires minimal force throughout both the raising and the lowering of the bed assembly, and is safely secured in an open, or lowered, position during use. The treadmill of the invention utilizes a unique cam assembly, including a torque rod and cam followers, to apply force acting against the weight of the bed assembly of the treadmill so as to not only reduce the force required to raise and lower the bed assembly, but also provides a significant safety feature by preventing the bed assembly from falling precipitously to the floor if released at any point in its travel between vertical and horizontal positions. The cam assembly also acts to secure the bed assembly in the fully open position, so as to provide a stable exercise platform during use of the treadmill, from which it can be easily released and returned to the closed position when use of the treadmill is completed.
The cam assembly includes a torque tube subassembly, with a pair of cam followers that act against a pair of uniquely designed cams. The torque tube subassembly includes a hollow tube, a pair of internal torque rods in the interior of the tube, each of which is connected to the tube and to a mounting arm which is firmly connected to the fixed frame of the treadmill. The tube is allowed to rotate around its longitudinal axis, and has a cam follower connected at each end. Each of the cam followers includes a roller at its outer end to contact and roll along the curved edge of one of the cams. The cams are mounted to the frame of the bed assembly, and move with that pivoting or folding bed assembly. Each cam has one flat edge that is received against the bed assembly frame, and one convexly curved edge along which the roller of the associated cam follower moves.
When the bed assembly of the treadmill is in the raised, or closed, position, the torque rods of the torque tube subassembly are generally relaxed, with minimal torsional load, and the cam followers are near the inner ends of the cams, where the distance between the flat and curved edges of the cams is least. As the bed assembly is rotated the cams move with the bed assembly and force the cam followers downward, increasing the torsional load on the torque rods. The rollers of the cam followers also move along the curved edge of the cam, which increases in distance from the flat edge of the cam toward the midpoint of the length of the cam. As the torsional load on the torque rods increases the force imposed by the cam followers against the cam increases, acting against the movement of the bed assembly with increasing force as the torsional load increases. The distance between the curved edge of each cam and the flat edge increases through, generally, the midpoint of the cam, and then begins to decrease toward the outer end of the cam. As a result, the rotational displacement of the cam followers attributable solely to the cams increases until the rollers of the cam followers pass, generally, the midpoint, and then decreases. However, the movement of the cams due to rotation of the bed assembly also causes a rotational displacement of the cam followers and an increase in torsional load of the cam followers. As the bed assembly is rotated around the hinge points from a closed, generally vertical, position toward an open, generally horizontal, position the center of mass is moved away from vertical alignment with the hinge and the force required to balance the bed assembly against the force of gravity increases. The components of the cam assembly are designed and adapted such that the vertical component of the force imposed by the cam followers closely balances the opposite vertical component of the gravitational force through the majority of the range of motion of the bed assembly. Accordingly, a user need apply minimal force to move the bed assembly through the majority of its range of motion during the opening and closing process.
For stability and safety, it is desirable for the bed assembly to be securely retained in both the closed position, for storage and in the open position, for use. Retention of the bed assembly in the closed position is preferably accomplished with a latch mechanism that must be released before the bed assembly can be pivoted open for use. Retention of the bed assembly in the open position is accomplished by providing a detent in the cams at their outer ends, which reduces the balancing force imposed by the cam assembly. When the bed assembly passes through a generally horizontal orientation as it is being opened and the outer end of the bed assembly continues downward into contact with the floor, the rollers of the cam followers move along the curved edge of the cam through a region of rapidly decreasing distance between the cam edges and into the detent, relieving a portion of the balancing force imposed by the cam assembly against the bed assembly so that the outer end of the bed assembly is held in firm contact with the floor by a portion of its own weight. When the bed assembly is to be closed, a sufficient lifting force must be imposed on the bed assembly to lift the outer end from the floor and move the cam follower rollers out of the detent and back into a position on the cam to more fully balance the weight of the bed assembly and allow the closing operation to be completed easily.
The structure and features of the preferred embodiment of the treadmill of the invention will be described in more detail with reference to the accompanying drawing figures.